Compress a file, but don't delete the original

Compress or decompress .xz and .lzma files.
More information: <https://tukaani.org/xz/format.html>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

xz -k {{file}}

click the source code to copy install xz on any operating system with command-not-found.com